In wireless communication systems, a radio access network generally comprises one or more access nodes (such as a base station) which communicate on radio channels over a radio or air interface with plural wireless terminals. In some technologies such a wireless terminal is also called a User Equipment (UE). A group known as the 3rd Generation Partnership Project (“3GPP”) has undertaken to define globally applicable technical specifications and technical reports for present and future generation wireless communication systems. The 3GPP Long Term Evolution (“LTE”) and 3GPP LTE Advanced (LTE-A) are projects to improve an earlier Universal Mobile Telecommunications System (“UMTS”) mobile phone or device standard in a manner to cope with future requirements.
In typical cellular mobile communication systems, the base station broadcasts on radio channels certain information which is required for mobile stations to access to the network. In Long-Term Evolution (LTE) and LTE Advanced (LTE-A), such information is called “system information” (“SI”). Each access node, such as an evolved NodeB (“eNB”) or a gNodeB (“gNB”) in the 5G New Radio (NR) System, broadcasts such system information to its coverage area via a Master Information Block (MIB) and several System Information Blocks (SIBs) on downlink radio resources allocated to the access node.
3rd Generation Partnership Project (“3GPP”) documents describe how capabilities of the wireless terminal (UE) may be communicated to the access node. See, for example, 3GPP TS 36.331 V15.1.0 (2018-03), Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification (Release 15) and 3GPP TS 38.331 V15.1.0(2018-03)3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Radio Resource Control (RRC) protocol specification, Release 15, both of which are incorporated herein by reference in their entirety. For example, section 5.6.3 of TS 36.331 describes a procedure wherein an eNB and/or gNB can request the UE to transfer a list of certain capabilities as determined by eNB/gNB. The purpose of the procedure, shown also in FIG. 1, is to transfer UE radio access capability information from the UE to E-UTRAN. If the UE has changed its E-UTRAN radio access capabilities, the UE shall request higher layers to initiate the necessary non-access stratum (NAS) procedures (see 3GPP TS 23.401) that would result in the update of UE radio access capabilities using a new RRC connection. The E-UTRAN initiates the procedure to a UE in RRC_CONNECTED when it needs (additional) UE radio access capability information. The E-UTRAN also determines which list of capabilities is requested as described in 3GPP TS 36.331 v.15.1, § 5.6.6.3.
Currently, 3GPP RAN2 is discussing ways to introduce new and enhanced features while also to reducing signaling. Information about the UE capability is one of these issues under considerations in New Radio (NR) design. It was agreed in RAN2#97 that the following are important to consider in developing a general solution to the capability issue:
1: Hardware sharing between New Radio (NR) and other things, e.g. Wireless Local Area Network (LAN), Bluetooth® (BT), Global Positioning System (GPS), etc;
2: Interference between New Radio (NR) and other things, e.g. WLAN, BT, GPS, etc;
3: Exceptional UE issues (e.g. overheating problems)
It was also agreed that UE radio access capabilities are generally to be considered as static and therefore that any change to UE radio access capabilities is considered just to temporarily (e.g., under network control) limit the availability of some capabilities, e.g., due to hardware sharing, interference or overheating.
Furthermore, it was agreed that a temporary capability restriction should be RAN-specific, and thus transparent to the Next Generation (NG) core, i.e., only a static capability is stored in the NG core and that the signaling concerning a temporary capability restriction request should be between the UE and an access node, e.g., the gNB.
Several proposals concerning UE radio access capabilities have been introduced, e.g., R2-1808264, R2-1807607, R2-1807534, R2-1807084, all of which are incorporated herein by reference in their entirety. However, these proposals add more complexity and procedural interactions between the UE and gNB which adversely affect overall performance and increase rather than reduce signaling.
What is needed, therefore, and an example object of the technology disclosed herein, are methods, apparatus, and techniques for determining/declaring and/or indicating/communicating UE capability limitation(s)/restriction(s) between a wireless terminal (UE) and an access node.